The present application is in the field of pneumatic tools, such as pneumatic wrenches and the like. Conventional pneumatic tools are actuated by compressed air supplied through an air supply channel to an air-driven motor. Typically, the air pressure supplied to the air-driven motor is determined by the compressed air source. The compressed air supply varies from shop to shop, and can even vary within a shop, for example due to concurrent usage by multiple users, and/or by sustained usage by one or more users. In order to accommodate continuous and multiple users the compressed air reservoir may be maintained at a relatively high design pressure, so that the compressed air source will maintain an adequate pressure even during heavy usage.
The torque output of the air-driven motor is dependent on the pressure level of the compressed air supplied to the air motor. In conventional systems, therefore, the torque output of a pneumatic hand tool may vary, depending on the current status of the air pressure supplied to the tool. Similarly, the torque output of a pneumatic tool may vary as the tool is attached to different sources of pressurized air.
It will also be appreciated that the use of a higher pressure than needed in a pneumatic tool may produce undue mechanical stress on the workpiece, and may produce undesirably stresses on the tool and in particularly on the air motor, potentially shortening the life of the tool or increasing the maintenance costs.